The present invention relates generally to fabrication of microelectronic devices, and specifically to a novel, miniaturized chamber for use in semiconductor wafer processing.
The use of air bearings is well known in a variety of mechanical applications. Such bearings operate by creating a high-pressure cushion of gas between two surfaces in relative motion. The air bearing reduces the friction between the surfaces to a negligible level, and allows the surfaces to be held in very precise mutual alignment by proper control of the gas pressure. Due to the lack of friction, air bearings are generally characterized by low wear and, consequently, absence of particle generation due to such wear. For example, Anorad (Hauppauge, N.Y.) produces linear positioning stages based on high-performance air bearings. Air Bearing Technology (Hayward, Calif.) produces air bearing spindles and disk chucks, as well as ancillary equipment.
The use of air bearings in semiconductor processing equipment is also known in the art. For example, U.S. Pat. No. 5,898,179, whose disclosure is incorporated herein by reference, describes mechanical scanning apparatus for moving a semiconductor wafer inside a vacuum chamber, based on air bearing seals. The apparatus includes differentially-pumped integral air bearing vacuum seals that support both linear and rotary motion. The air bearing seals are produced by a combination of nozzles and vacuum grooves between the surfaces to be sealed. Gas is injected through the nozzles in order to create a high-pressure cushion between the surfaces, which also acts as a barrier to keep ambient air from entering the vacuum chamber. The gas is pumped out through the vacuum grooves in order to maintain a high vacuum within the chamber.
It is an object of some aspects of the present invention to provide improved apparatus and methods for processing a substrate under controlled atmospheric conditions, and particularly for processing semiconductor wafers and other elements used in producing microelectronic devices.
Preferred embodiments of the present invention provide a micro-chamber for processing of substrates such as semiconductor wafers. Rather than encompassing the entire substrate, in the manner of processing chambers known in the art, the micro-chamber covers and processes only a small area of the surface of the substrate at any one time. An air bearing seal is created between the periphery of the micro-chamber and the surface. This seal permits the micro-chamber to scan over the substrate without damage to the surface, while maintaining controlled atmospheric conditionsxe2x80x94either vacuum or positive pressurexe2x80x94within the micro-chamber. By scanning the micro-chamber over the surface, typically using a linear mechanical scanner or a combination of linear and rotary scanning motions, the entire substrate can be processed. Multiple micro-chambers, each performing a different process step, may be controlled to scan the surface together (in a desired sequence) within a single processing tool.
Micro-chambers in accordance with preferred embodiments of the present invention can thus be used to reduce the size and increase the efficiency of wafer fabrication equipment. Because of the small volume of the micro-chambers, the quantity of chemicals and gases that they must use to carry out a given process step is typically small, thus saving on manufacturing costs and minimizing contamination and environmental pollution. Furthermore, maintaining process uniformity within the small processing volume of the micro-chamber is much easier than in a large chamber that can contain the entire wafer. As noted above, the micro-chamber can be scanned over the entire wafer, while maintaining uniform process conditions, so that the entire wafer is processed uniformly.
In some preferred embodiments of the present invention, a micro-chamber is used for particle removal and surface cleaning of semiconductor wafers and of other manufacturing elements, such as masks and reticles. The high-pressure gas injected into the bearing region around the micro-chamber creates an aerodynamic shearing force at the surface, which is helpful in dislodging contaminants from the surface. Within the micro-chamber, various means may be used for cleaning the surface, including (but not limited to) laser irradiation, particle bombardment, plasma generation, liquid and gaseous agents, and other means known in the art. Alternatively or additionally, micro-chambers may be used for other process steps, such as etching and passivation.
There is therefore provided, in accordance with a preferred embodiment of the present invention, apparatus for processing a surface of a substrate, including:
a chamber, including a chamber wall defining a cavity having one side that is open, the chamber wall including a lip surrounding the open side of the cavity; and
gas ports disposed within the chamber wall and opening through the lip, the gas ports being adapted to emit a pressurized gas so as to create a gas cushion between the lip and the surface when the open side of the cavity is placed adjacent to the surface, thus creating a seal between the cavity and an environment external to the chamber.
Preferably, the apparatus includes a vacuum manifold for evacuating the chamber while the gas cushion maintains the seal between the cavity and the environment, wherein the vacuum manifold is disposed within the chamber wall and opens through the lip between the gas ports and the cavity.
In a preferred embodiment, the gas ports are adapted to emit the pressurized gas so as to create an aerodynamic shear force, which is effective to dislodge contaminants from the surface.
Preferably, the apparatus includes means disposed within the chamber for applying a manufacturing process to an area of the surface adjacent to the open side of the cavity. Most preferably, the means for applying the manufacturing process include means for cleaning the surface. Additionally or alternatively, the means for applying the manufacturing process include an inlet port, which is adapted to convey at least one of a gas, a vapor, a liquid and a stream of frozen particles into the cavity, and/or a radiation guide, which is adapted to direct radiation toward the area of the surface adjacent to the open side of the cavity. Typically, the substrate includes a semiconductor wafer, and the manufacturing process includes a process for fabricating microelectronic devices on the wafer.
Preferably, the apparatus includes a motion device, which is coupled to scan the chamber over the surface while maintaining the seal between the lip and the surface. Most preferably, the motion device includes a rotation mechanism, which is adapted to rotate the substrate about a rotation axis, and a translation mechanism, which is adapted to translate the chamber over the surface in a radial direction relative to the rotation axis.
There is also provided, in accordance with a preferred embodiment of the present invention, a method for processing a surface of a substrate, including:
placing a chamber that contains a cavity having one side that is open so that the open side of the cavity is adjacent to the surface; and
directing a flow of a gas through a lip of the chamber surrounding the open side of the cavity so as to create a gas cushion between the lip and the surface, thus creating a seal between the cavity and an environment external to the chamber.
In a preferred embodiment, placing the chamber includes placing multiple chambers at respective positions adjacent to the surface, and directing the flow of the gas includes sealing each of the chambers against the surface, and applying the manufacturing process includes operating each of the chambers to apply a respective portion of the process. Preferably, operating each of the chambers includes operating at least first and second ones of the chambers to apply successive, first and second steps of the process, respectively.
There is additionally provided, in accordance with a preferred embodiment of the present invention, apparatus for processing a surface of a substrate, including:
a plurality of chambers, each such chamber including a chamber wall defining a cavity having one side that is open, the chamber wall including a lip surrounding the open side of the cavity;
gas ports disposed within the chamber wall and opening through the lip of each chamber, the gas ports being adapted to emit a pressurized gas so as to create a gas cushion between the lip and the surface when the open side of the cavity is placed adjacent to the surface, thus creating a seal between the cavity and an environment external to the chambers; and
means disposed within each chamber for applying a respective portion of a manufacturing process to an area of the surface adjacent to the open side of the cavity.
The present invention will be more fully understood from the following detailed description of the preferred embodiments thereof, taken together with the drawings in which: